Preimplantation genetic diagnosis of DiGeorge syndrome.

We report the first case of preimplantation genetic diagnosis used in order to avoid chromosomal imbalance in the progeny of a woman mildly affected by DiGeorge syndrome and carrier of a microdeletion of chromosome 22q11.2. In total, seven embryos were biopsied in three separate treatments and analysed by fluorescent in-situ hybridization (FISH). Of these, four were carrying the deletion, two were normal and in one the analysis was inconclusive. The diagnostic procedure was performed within 5 h. This allowed the biopsied embryos to be transferred the same day as the biopsy was taken (day 3). Two embryos were transferred in the third treatment, but no pregnancy was established. Patients with a 22q11 microdeletion, who have a 50% risk of transmitting the deletion to their offspring, can now be offered preimplantation genetic diagnosis using FISH for the detection of a 22q11 deletion.